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NBME 21 Answers

nbme21/Block 2/Question#31

A 37-year-old man is brought to the emergency ...

Intercostal

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 +4  upvote downvote
submitted by hayayah(379),

With this question, I think they want you to recognize that the patient isn't having chest pain related to the heart. They emphasize several rib fractures and a pneumothorax but don't indicate any heart damage (lack of adventitious sounds = no pulmonary edema indicated or a lung issue related to heart problem).

The pericarditis is what's innervated by the phrenic n. Seeing as how his heart is fine, the fractured ribs are probably what are causing him pain via the intercostal nerves.

didelphus  Visceral pain is typically poorly localized (heart attacks are usually described as "crushing pressure" that radiates to the shoulder or neck), so this patients "sharp" right-sided pain in the setting in multiple right-sided rib fractures is likely related to the ribs. The intercostals run with the ribs and provide sensation to the chest wall. +3  




 +3  upvote downvote
submitted by sweetmed(33),

Pain fibers for Parietal pleura: Cervical and Costal parts is by Intercostal Nerve, Diaphragmatic and Mediastinal via Phrenic Nerve. Rib cage injury causes costal pleural pain.





 +2  upvote downvote
submitted by vlodkadrinker(6),

why? like does my med school suck or am I just that dumb cuz we never learned anything like this

sklawpirt  I think its just that the patient is CONSCIOUSLY experiencing chest pain. Because he is consciously feeling the pain and would be able to directly point to it (and that it is not referred visceral pain) it has to be a somatic afferent nerve fiber. This narrows it down exclusively to the intercostal nerve exc;usively. https://en.wikipedia.org/wiki/Intercostal_nerves IMportant to the patients "right sided chest pain" is his history of MVA and x-ray confirming multiple rib fractures. I think this is correct? Does that make sense ? All of the other choices do not carry SA fibers in that area +5  




 +0  upvote downvote
submitted by yssya1992(2),

The idea to know its a somatic pain so in other choices only its could be phrenic or intercostal Phrenic usually will mentioned radiating to shoulder in adition what mentioned above about phernic nerve innervation for parietal pleural





 +0  upvote downvote
submitted by yssya1992(2),

The idea to know its a somatic pain so in other choices only its could be phrenic or intercostal Phrenic usually will mentioned radiating to shoulder in adition what mentioned above about phernic nerve innervation for parietal pleural





 +0  upvote downvote
submitted by burak(4),

Costal and cervical pleura is innervated by inercostal nerve, mediastinal and diaphragmatic pleura is innervated by phrenic nerve.Intercostal nerva pain typically felt closer to the pain, phrenic nerve (C3-5) pain is radiated pain by SUPRACLAVICULAR nerve area (shoulder). Uw question ID: 1535